Vertical filling-packaging machine

ABSTRACT

There is provided a vertical filling-packaging machine capable of feeding fluidized content material into a tubular film with good quantitative accuracy and in which air bubbles are mixed into the content material. The packaging machine according to the present invention performs an operation of feeding content material through injection nozzle ( 15 ) into tubular film ( 1 ′) that includes a bottom portion. This packaging machine performs an operation of transporting the tubular film downward, and an operation of tightly sealing the tubular film by heat sealing using lateral sealing mechanism ( 60 ). Lower end ( 15   a ) of the injection nozzle is configured to be immersed in the content material throughout entirety of the series of packaging operations, and the operation of feeding the content material starts in a state in which the injection port of the injection nozzle is immersed in the content material.

TECHNICAL FIELD

The present invention relates to a vertical filling-packaging machine which forms a long film drawn from a feed roll into a tubular film and feeding content material thereinto, thereby manufacturing a packaging bag (packaged product), and more particularly to a vertical filling-packaging machine which feeds the content material through an injection nozzle into the tubular film that includes a bottom portion.

BACKGROUND ART

There has been known a packaging machine which continuously manufactures a packaging bag filled with content material such as liquid (for example, see Japanese Patent Laid-Open No. 2005-112359). The packaging machine manufactures the packaging bag by folding a long sheet of film drawn from a feed roll to form a tubular shape and by injecting the content material into the tubular film or forming a predetermined seal portion. Hereinafter, a typical packaging operation will be described with reference to FIG. 1.

FIG. 1A illustrates an initial state of the packaging operation, in which lateral seal portion F2 formed in the previous process is formed at the lower end portion of tubular film 1′, thereby allowing tubular film 1′ to have a bottom portion. A pair of squeezing rollers 45 is used to squeezingly divide the content material injected into the tubular film. Lateral seal 60 is used to tightly seal an upper opening portion of the tubular film.

Following the initial state of FIG. 1A, as shown in FIG. 1B, first, the pair of squeezing rollers 45 is driven so as to pinch tubular film 1 therebetween. Thus, the content material inside tubular film 1′ is divided into upper and lower portions. Since squeezing rollers 45 squeezingly pinch the portion in which the content material is present, in this way, the amount of air mixed into the final packaging bag 91 can be minimized.

Then, as shown in FIG. 1C, when squeezing rollers 45 are rotated, void-filled portion 2 in which no content material exists is formed on tubular film 1′, which is transported downward. When void-filled portion 2 reaches a position where it is to be pinched by lateral sealing mechanism 60, lateral sealing mechanism 60 pinches void-filled portion 2.

Then, as shown in FIG. 1D, lateral sealing mechanism 60 is moved downward in a state in which the tubular film is pinched, thereby forming lateral seal portion F2. During this process, the content material continues to be fed from injection nozzle 15 and the fed content material is accumulated in an upper area higher than squeezing rollers 45.

Then, as shown in FIG. 1E, when lateral sealing mechanism 60 completes heat sealing and cutoff operations, one packaging bag 91 filled with content material is obtained. In the meantime, the pair of squeezing rollers 45 is opened, whereby the content material that has been accumulated in the area higher than squeezing rollers 45 are dropped downward. Subsequently, lateral sealing mechanism 60 is moved back to the original position to return to the initial state of FIG. 1A.

As another technique related to the packaging machine of the present invention, there has been known a mechanism for, when one feed roll is used up, joining the end portion of a film of the feed roll to the start portion of a film of another feed roll to be used (see Japanese Patent Laid-Open No. H09-58616). The use of such a mechanism can eliminate the need of troublesome work such as setting a film again each time one feed roll has been used up.

However, such packaging operations as shown in FIGS. 1A to 1E have a problem in that when content material is fed from the injection nozzle into a tubular film, a variation occurs in the amount of fed content material or bubbles of air or the like are mixed into the content material for the reasons described below.

As shown in FIG. 2, the packaging operation of FIG. 1 is configured such that when squeezing rollers 45 are opened, the content material is dropped downward, and such that when the content material is dropped, lower end 15 a of the injection nozzle is exposed. In the state as shown in FIG. 2A, injection nozzle 15 is filled with the content material. However, as shown in FIG. 2B, when the lower end of the nozzle is exposed and open to air, the content material remaining inside the nozzle is also dropped into the tubular film.

This means that the injection nozzle is emptied. When content material is fed through such an emptied nozzle, the content material gradually flows downward inside the emptied nozzle, so that it is difficult to feed the content material with good quantitative accuracy.

In addition, as shown in FIG. 2B, when content material is fed in a state in which lower end 15 a of the nozzle is exposed, lower end 15 a is positioned higher than the liquid level, and thus there is also a problem in that when content material is injected, air bubbles tend to be mixed into the content material. Such an air bubble mixture means that air remains in the final packaged product. For example, if the content material is food, such an existence of air therein contributes to the quality degradation of the content material.

The present invention has been made with a view to solving the above-described problems, and an object of the present invention is to provide a vertical filling-packaging machine capable of feeding fluidized content material into a tubular film with good quantitative accuracy and with few air bubbles mixed into the content material.

DISCLOSURE OF THE INVENTION

In order to achieve the above object, a vertical filling-packaging machine comprises: an injection nozzle for feeding content material that is fluidized into a tubular film that includes a bottom portion; transport means for transporting the tubular film downward in a state in which the content material is fed thereinto; and a lateral sealing mechanism for tightly sealing the tubular film by heat sealing a portion of the tubular film,

wherein the vertical filling-packaging machine manufactures a packaged product by a series of packaging operations including at least following operations: an operation of feeding the content material through the injection nozzle; an operation of transporting the tubular film downward in a state in which the content material is fed thereinto; and an operation of heat sealing by the lateral sealing mechanism,

wherein an injection port of the injection nozzle is configured to be immersed in the content material throughout entirety of the series of packaging operations, and the operation of feeding the content material starts in a state in which the injection port of the injection nozzle is immersed in the content material.

According to the packaging machine of the above present invention, the operation of feeding the content material starts in a state in which the injection port of the injection nozzle is immersed in the content material. Therefore, compared to the proposed feeding method as shown in FIG. 2, bubbles of air or the like are difficult to be mixed into the content material.

In addition, the injection port of the injection nozzle is configured to be always immersed in the content material during the series of packaging operations (in other words, the injection port of the injection nozzle is configured not to be opened to air), so that the inside of the injection nozzle is configured not to be emptied. Therefore, compared to the proposed feeding method as shown in FIG. 2, the quantitative accuracy of the content material to be fed is improved.

The above vertical filling-packaging machine may further include a pair of squeezing rollers which pinches the portion of the tubular film in which the fed content material is present, and which rotates in a state in which the pair of squeezing rollers which pinches the portion of the tubular film in which the fed content material is present, thereby forming a flat void-filled portion on the tubular film and transporting the tubular film downward. The operation of feeding the content material may be to feed the content material into the tubular film that is located higher than the portion that is pinched by the pair of squeezing rollers. In this case, the content material that has been accumulated in a position higher than that of the squeezing rollers may be dropped downward into the tubular film located lower than the squeezing rollers at the same time when the pair of squeezing rollers is opened, and after the content material is dropped, liquid level of the content material may be configured to be higher than the injection port of the injection nozzle.

The above vertical filling-packaging machine may further include a content material feeding mechanism including: a reservoir tank for reserving the content material; a feed passage for transferring the content material from the reservoir tank to the injection nozzle; pump means used as a driving source for transferring the content material from the reservoir tank to a side of the injection nozzle; a return passage for returning the content material from the side of the injection nozzle to the reservoir tank; and valve means capable of switching between an operation of feeding the content material, which has been transferred through the feed passage, into the tubular film through the injection nozzle and an operation of returning the content material, which has been transferred through the feed passage, back to a side of the reservoir tank.

The above vertical filling-packaging machine may further include a film feeding device which holds two feed rolls, joins an end portion of a first film drawn from one of the feed rolls to an end portion of a second film drawn from the other of the feed rolls, and feeds the joined first and second films as a long film; and a vertical sealing mechanism which performs vertical sealing on side edge portions of the long film along a longitudinal direction of the long film so as to change the long film into the tubular film. The above vertical filling-packaging machine may be configured such that the vertical sealing mechanism performs vertical sealing on a joint portion in which the first film and the second film are joined in a state in which an operation of transporting the long film is terminated, and the valve means of the content material feeding mechanism is switched to a position on a side of returning the content material to the side of the reservoir tank while the vertical sealing operation is being performed on the joint portion. In this case, the time to perform vertical sealing on the joint portion may be configured to be longer than the time to perform an ordinary vertical sealing so as to prevent the content material from leaking from a vertical sealed portion formed by the vertical sealing.

As described above, according to the vertical filling-packaging machine of the present invention, the operation of feeding content material starts in a state in which the injection port of the injection nozzle is inside the content material, whereby the content material can be fed with good quantitative accuracy, and air bubbles mixed into the content material can be minimized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates an example of a proposed packaging operation;

FIG. 1B illustrates an example of a proposed packaging operation;

FIG. 1C illustrates an example of a proposed packaging operation;

FIG. 1D illustrates an example of a proposed packaging operation;

FIG. 1E illustrates an example of a proposed packaging operation;

FIG. 2A explains a problem that a proposed packaging operation has;

FIG. 2B explains a problem that a proposed packaging operation has;

FIG. 3 schematically illustrates an example of a vertical filling-packaging machine of the present invention;

FIG. 4 is a perspective view explaining a joint portion between films;

FIG. 5 illustrates a configuration of a content material feeding mechanism, one of features of the present invention;

FIG. 6 illustrates a pillow type packaging bag capable of being manufactured by the packaging machine of FIG. 3;

FIG. 7A is a process view explaining a packaging operation of the packaging machine of FIG. 3;

FIG. 7B is a process view explaining a packaging operation of the packaging machine of FIG. 3;

FIG. 7C is a process view explaining a packaging operation of the packaging machine of FIG. 3;

FIG. 7D is a process view explaining a packaging operation of the packaging machine of FIG. 3;

FIG. 7E is a process view explaining a packaging operation of the packaging machine of FIG. 3;

FIG. 8 is a timing chart showing the timing of the operation of an individual component of the packaging machine of FIG. 3;

FIG. 9 illustrates a packaging bag including a joint portion of films;

FIG. 10A illustrates a configuration of an injection nozzle of the packaging machine of FIG. 3; and

FIG. 10B illustrates another configuration of the injection nozzle of the packaging machine of FIG. 3.

DESCRIPTION OF SYMBOLS

-   -   1A, 1B Film     -   1′ Tubular film     -   2 Void-filled portion     -   5 Joint portion     -   10 Vertical filling-packaging machine     -   10A Film feeding mechanism     -   14 Folding guide     -   15 Injection nozzle     -   15 a Lower end     -   17 Injection port     -   20 Content material feeding mechanism     -   30 Vertical sealing mechanism     -   41 Transport roller     -   45 Squeezing roller     -   60 Lateral sealing mechanism     -   61 Heater bar     -   62 Heater bar receiver     -   71 Joint sealer     -   83 Sensor     -   91, 92 Packaging bag     -   F1 Vertical sealed portion     -   F2 Lateral sealed portion     -   Ra, Rb Feed roll

BEST MODE FOR CARRYING OUT THE INVENTION

As shown in FIG. 3, packaging machine 10 of the present embodiment includes film feeding mechanism 10A that draws a film from feed rolls Ra and Rb, and joins film 1A and film 1B as needed. Further, packaging machine 10 includes packaging mechanism 10C that forms the film unrolled from film feeding mechanism 10A into a tubular shape, and that continuously manufactures a packaging bag by forming a vertical sealed portion and a lateral sealed portion thereon as needed.

As film feeding mechanism 10A, a proposed film feeding mechanism, which includes a general configuration for such a packaging machine, can be used. Film feeding mechanism 10A shown in FIG. 3 uses two feed rolls Ra and Rb, and is configured such that, for example, when film 1A of feed roll Ra has been used up, film 1B of feed roll Rb is continuously unrolled. It should be noted that FIG. 3 shows that film 1A is drawn into a side of the packaging mechanism 10C as a film on the using side, and that film 1B is held in the vicinity of joint sealer 71 as a film on the standby side.

A configuration is made such that, for example, sensor 83 can detect that film 1A on the using side runs short, and joint sealer 71 is driven on the basis of the detected result. Thus, the end portion of using side film 1A and the end portion of standby side film 1B are heat-sealed so as to join the two films together. More specifically, as shown in FIG. 4, two films 1A and 1B are partially overlapped and two films are joined together by forming sealed portion 3. The region in which these two films are overlapped and the region in which sealed portion 3 is formed is called “joint portion 5”.

According to packaging machine 10 of the present embodiment, the use of film feeding mechanism 10A as described above allows a film to be continuously fed into packaging mechanism 10C. Such a capability of continuously feeding a film is very advantageous in that there is no need to temporarily terminate manufacturing a packaging bag.

Now going back to FIG. 3, packaging mechanism 10C will be described. It should be noted that packaging mechanism 10C is the same as the vertical filling-packaging machine disclosed in the Applicant's Japanese Patent Laid-Open No. 2004-276930.

Packaging mechanism 10C includes folding guide 14 for folding a film into a tubular shape; vertical sealing mechanism 30 which performs vertical sealing on the side edges of films folded by folding guide 14 to form vertical sealed portion F1 (see FIG. 6) and to form tubular film 1′; and a pair of transport rollers 41, a pair of squeezing rollers 45 and lateral sealing mechanism 60, each of which arranged on the downstream side in the film transport direction from vertical sealing mechanism 30.

Vertical sealing mechanism 30 is provided with heater bar 31 incorporating heating means such as a heater. Heater bar 31 is configured to be able to advance and retreat (in the lateral direction in the figure) with respect to the film and also to move back and forth in the up/down direction in the figure, thereby providing a box-shaped motion as shown by arrow A₃₀ of FIG. 3.

Vertical sealing mechanism 30 performs sealing operation as follows. First, heater bar 31 moves in the direction of coming close to a film while in a state remaining at an ascending end position thereof, thereby allowing the film to be pinched between heater bar 31 and a main pipe (not shown). Then, in this pinched state, heater bar 31 moves downward in FIG. 3 in synchronism with the film transport. The film to be heat-sealed receives heat from heater bar 31, and both side edges of the film are joined together. When heater bar 31 reaches a descending end position thereof, heater bar 31 moves away from the film and returns to the original height.

The above vertical sealing operation is repeated to form a continuous vertical sealed portion on an overlapped portion of both side edges of the film. The vertical sealing mechanism performing such a box-shaped operation has an advantage of being capable of forming a vertical sealed portion without terminating the film transport.

It should be noted that tubular film 1′ is transferred in a state of including a substantially circular cross section, namely, in a state of including a space inside tubular film 1′ until tubular film 1′ passes through vertical sealing mechanism 30. When tubular film 1′ goes further downstream, tubular film 1′ is changed into a flat pressed shape by a guide plate (not shown) provided between vertical sealing mechanism 30 and transport rollers 41.

Transport rollers 41 are arranged so as to pinch both side edges in the width direction of tubular film 1′ pressed in this manner. Transport rollers 41 are one of film transport means in packaging mechanism 10C. When rotated, transport rollers 41 transport tubular film 1′ downward.

A pair of squeezing rollers 45 pinches the tubular film so as to divide filling material injected into the tubular film. When squeezing rollers 45 are rotated in this state, a void-filled portion including no filling material therein is formed on the tubular film, and the tubular film is transported downward. An advantage of forming such a flat void-filled portion is to enable the suppression of the occurrence of sealing failure during the lateral sealing operation described below.

Lateral sealing mechanism 60 includes heater bar 61 incorporating heating means such as a heater, and heater bar receiver 62 arranged facing heater bar 61. The pair of members is used to pinch tubular film 1′ and heat the film, thereby forming lateral sealed portion F2 (see FIG. 6) on the film.

Heater bar 61 and heater bar receiver 62 are configured to perform a box-shaped motion in the same way as for vertical sealing mechanism 30. More specifically, as shown by arrow A₆₀ of FIG. 3, heater bar 61 and heater bar receiver 62 with tubular film 1′ pinched therebetween move downward in synchronism with the film transport. Heater bar 61 and heater bar move away from the film at the descending end position, and go back to the original position again.

It should be noted that heater bar 61 incorporates a cutter (not shown) for separating a packaging bag from tubular film 1′ by cutting lateral sealed portion F2. In addition, in response thereto, heater bar receiver 62 includes a relief groove formed so as to provide space between the protruded cutter and heater bar receiver 62.

Subsequently, the content material feeding mechanism, one of features of the packaging machine of the present embodiment, will be described with reference to FIG. 5. It should be noted that vertical sealing mechanism 30 is not shown in FIG. 5, but this is not an essential matter.

As shown in FIG. 5, content material feeding mechanism 20 includes reservoir tank 22 for reserving the content material; feed passage 21 a for transferring the accumulated content material to injection nozzle 15; and pump 23 used as a driving source for transferring the content material. Further, in the present embodiment, there is return passage 21 b for returning the content material from a side of the injection nozzle 15 to a side of the reservoir tank 22. Three-way-valve 25 is provided to switch between the operation (referred to as “first mode”) of feeding the content material transferred to a side of the injection nozzle into the tubular film and the operation (referred to as “second mode”) of returning the content material through return passage 21 b back to reservoir tank 22.

When three-way-valve 25 is switched to “first mode” in a state in which pump 23 is being driven, the content material is fed into tubular film 1′ through injection nozzle 15. On the contrary, when three-way-valve 25 is switched to “second mode” in a state in which pump 23 is being driven, the operation of feeding the content material into the tubular film is terminated, and the content material is returned to a side of the reservoir tank 22 through return passage 21 b.

Such a configuration is advantageous in that the operation of feeding the content material into the tubular film can be controlled simply by switching three-way-valve 25 while pump 23 is being driven. In general, it takes some time to stabilize the feed rate of pump 23. If intermittent feeding is performed by switching on/off pump 23, the amount of content material to be fed may vary.

In contrast, according to the configuration of the present embodiment, there is no need to terminate driving the pump and the pump feed rate is stable. Therefore, it is difficult for such a problem to occur. In addition, from another point of view, the fact that it is not necessary to terminate and to start driving the pump means that the burden applied to the pump is relieved, and thus pump failure can be minimized.

The type of the packaging bag manufactured by the vertical filling-packaging machine of the present invention is not limited to the type described above, but may be a packaging bag as shown in FIG. 6. Packaging bag 91 is a so-called pillow type packaging bag in which two lateral sealed portions F2 a and F2 b (hereinafter collectively referred to as “F2”) and vertical sealed portion F1 serving as a backlining are formed. The inside of packaging bag 91 is filled with fluidized content material (e.g., liquid). Vertical sealed portion F1 is a heat-sealed portion formed by vertical sealing mechanism 30, and lateral sealed portion F2 is a heat-sealed portion formed by lateral sealing mechanism 60.

Next, an example of the packaging operation by packaging machine 10 of the present embodiment configured as above will be described with reference to FIGS. 7 and 8. FIG. 7 is a process view explaining the packaging operation of packaging machine 10, and FIG. 8 is a timing chart showing the timing of the operation of an individual component thereof.

(Basic Packaging Operation)

First, the basic operation for manufacturing one packaging bag 91 will be described.

FIG. 7A illustrates the initial state of a series of packaging operations, which corresponds to the state of time “t_(A)” in FIG. 8. As shown in FIG. 7A, lateral seal portion F2 formed in the previous process is formed at the lower end portion of tubular film 1′, thereby allowing tubular film 1′ to have a bottom portion. A pair of squeezing rollers 45 and lateral sealing mechanism 60 are both in a state of being open.

Content material has already been injected into tubular film 1′, and the liquid level thereof is located in a position (height h1) higher than lower end 15 a of the injection nozzle. In other words, lower end 15 a of the injection nozzle is in a state of being immersed into the content material. When lower end 15 a is exposed to air, the content material inside the nozzle is dropped into the tubular film by its own weight, and thus the inside of the nozzle is in an empty state. In contrast, according to configuration of the present embodiment, since lower end 15 a of the nozzle is immersed into the content material, the content material is not dropped, and the inside of the nozzle remains in a state of being filled with the content material.

Then, as shown in FIG. 7B (see time “t_(B)” of FIG. 8), the pair of squeezing rollers 45 pinches a portion of tubular film 1′, in which the content material is present, therebetween. Thus, the content material in tubular film 1′ is divided into upper and lower portions. Such an operation of squeezing rollers 45 to pinch a portion in which the content material is present assures that air does not remain inside packaging bag 91. The operation of feeding content material into the tubular film has already started since the initial state as shown in FIG. 7A. Therefore, in the process of FIG. 7B, the liquid level rises to a level of being slightly higher than h1.

Then, as shown in FIG. 7C (see time “t_(C)” of FIG. 8), individual squeezing rollers 45 are rotated as shown by arrows in the figure while the operation of feeding the content material is continued, namely, without the feeding operation thereof being terminated. Hence, flat void-filled portion 2 including no content material therein is formed on tubular film 1′, which is transferred downward. It should be noted that although not shown in FIG. 7, the feeding operation is configured such that transport rollers 41 (see FIG. 3) are also rotatably driven in synchronism with the rotation of squeezing rollers 45, thereby supporting the film transport.

After void-filled portion 2 is transferred to a position to be pinched by lateral sealing mechanism 60, lateral sealing mechanism 60 pinches void-filled portion 2 and the lateral sealing operation starts.

Then, as shown in FIG. 7D (see time “t_(D)” of FIG. 8), in a state in which the tubular film is pinched by lateral sealing mechanism 60, lateral sealing mechanism 60 is moved downward in synchronism with the rotation of squeezing rollers 45. While being pinched by lateral sealing mechanism 60, tubular film 1′ is heated, thereby forming lateral sealed portion F2. Although detailed operation is not shown in the figure, after lateral sealing mechanism 60 reaches the descending end position, a cutter incorporated in the heater bar is protruded to cut and separate the packaging bag. During this process, the operation of feeding the content material continues, and the fed content material is accumulated to a level higher than the position of squeezing rollers 45. Liquid level height h2 in this process is the highest of all in the series of packaging operations, corresponding to the liquid level height “high” of FIG. 8.

Then, as shown in FIG. 7E (see time “t_(E)” of FIG. 8), both the operations of pinching the film by lateral sealing mechanism 60 and the pair of squeezing rollers 45 are stopped. Thereby, one packaging bag 91 filled with content material is obtained, and at the same time, content material that has been accumulated to a level higher than the position of squeezing rollers 45 is dropped downward into tubular film 1′.

What matters in the process of FIG. 7E is that a feeding operation is configured such that after the content material is dropped downward, the liquid level of the content material is higher than the position of lower end 15 a of the nozzle (specifically, the same liquid level height h1 as the initial state). Such a configuration assures that lower end 15 a of the nozzle remains to be immersed in the content material continuously during the series of packaging operations. Therefore, even after the content material inside the nozzle is dropped downward, the inside of the nozzle is not emptied. According to such a configuration in which the inside of the nozzle is filled with the content material and the operation of feeding the content material starts in this state, the content material can be fed with a very favorable quantitative accuracy. However, if the content material is injected in a state in which the lower end of the nozzle is exposed and where the inside of the nozzle is emptied, bubbles of air or the like are mixed into the liquid while the content material is being dropped downward. However, the above configuration can prevent such a problem from occurring.

As shown in FIG. 7E, finally, lateral sealing mechanism 60 is moved back to the original position and the packaging machine returns to the initial state of FIG. 7A. Packaging bag 91 can be continuously manufactured by repeatedly performing the series of packaging operation as described above.

With respect to the above described packaging operation, more specifically, the time per cycle shown in FIG. 8 may be, for example, 1.0 second. With respect to the operation of squeezing rollers 45, the time when squeezing rollers 45 are opened may be set to 0.4 seconds (corresponding to the individual process of FIGS. 7A and 7E), and the time when squeezing rollers 45 are closed may be set to 0.6 seconds (corresponding to the individual process of FIGS. 7B to 7E).

(Packaging Operation with Respect to Film Joint Portion)

By the way, if the filled content material is liquid or the like, and a sealing failure occurs in sealed portion F1 or F2, or joint portion 5 of packaging bag 10, the content material may leak from that place. For this reason, the individual sealed portions of such a packaging bag need to be reliably heat-sealed.

This will be described with reference to FIG. 9. As shown in the figure, if joint portion 5 of the films is located on the bellows of packaging bag 92, and, for example, if a sealing failure occurs in vertical sealed portion F1′ including joint portion 5, the content material will leak from that place. In particular, joint portion 5 is a portion where two films are overlapped, and thus, insufficient heat sealing in the vertical sealing operation may cause insufficient sealing strength. Accordingly, it is preferable to sufficiently heat seal vertical sealed portion F1′ including the joint portion.

However, since packaging bag 92 includes joint portion 5, the bag may be a defective product in the first place. Therefore, it is considered that such a packaging bag does not have to be filled with the content material. However, if the content material is not fed into the packaging bag, the following problem may occur.

For example, there is no problem in a case in which packaging bag 91 follows packaging bag 92 as shown in FIG. 9, but, if packaging bag 91 has already been cut and separated, emptied packaging bag 92 is in a state of hanging down at the bottom of the tubular film. Since packaging bag 92 is emptied, the tensile force, which is due to the weight of content material in packaging bag 92, is not applied to the tubular film. Therefore, the emptied packaging bag 92 may swingly move to be in contact with heater bar 61 (see FIG. 6). If packaging bag 92 is in contact with heater bar 61, the film may melt to adhere to the heater bar, which will disturb the film transport. In order to prevent such problem, it is preferable to feed the content material into packaging bag 92 in the same way as for other packaging bags.

The vertical sealing operation is configured such that the time of the vertical sealing operation to be performed in a region including joint portion 5 is longer than the time of an ordinary vertical sealing operation. Here, the “ordinary vertical sealing operation” refers to vertical sealing that is to be performed on a region not including joint portion 5. For example, the time of the ordinary vertical sealing operation may be 1 second; and the time of the vertical sealing operation that is to be performed in a region including joint portion 5 (hereinafter referred to as “film joint vertical sealing operation”) may be 4 seconds.

The film joint vertical sealing operation will be described with reference to the timing chart of FIG. 8 again.

This vertical sealing operation starts when joint portion 5 of the films reaches the position to be pinched by vertical sealing mechanism 30. For example, a sensor (not shown) for detecting joint portion 5 may be used to detect whether joint portion 5 reaches the position to be pinched by vertical sealing mechanism. Alternatively, back calculation may be made from the relation between the distance from joint sealer 71 (see FIG. 3) to vertical sealing mechanism 30 and the length of a film transferred per cycle; and after a predetermined number of ordinary vertical sealing operations is performed, the film joint vertical sealing operation may start.

The film joint vertical sealing operation starts when, as shown by time “t_(H)” of FIG. 8, the film transport is terminated, squeezing rollers 45 are opened, and the liquid level height is “high” (see FIG. 7D). According to the vertical sealing operation, the time when vertical sealing mechanism 30 pinches the film is set to, for example, 2.0 to 3.0 seconds. Since the pinching time for the ordinary vertical sealing operation is 0.4 seconds, the pinching time for the film joint vertical sealing operation is about five times longer than the ordinary time.

Three-way-valve 25 (see FIG. 4) is switched at time t_(H) when the content material transferred from reservoir tank 22 is returned to reservoir tank 22 through return passage 21 b. Here, pump 23 continues to be driven, so that the content material circulates from feed passage 21 a through the three-way-valve and return passage 21 b to reservoir tank 22.

As described above, during the film joint vertical sealing operation, the content material is configured to circulate, thereby preventing more content material than is necessary from being fed into tubular film. The feeding of the content material can be controlled, for example, by temporarily terminating the driving of pump 23. However, as described above, controlling the feeding of the content material by turning on/off the pump tends to cause the amount of feeding content material to vary. In contrast, the present embodiment is configured to control the feeding of the content material just by switching three-way-valve 25 while pump 23 is being driven. Since the feeding rate of pump 23 is stable, it is difficult for a problem such as a reduction in quantitative accuracy to occur.

The use of three-way-valve 25 to switch the feeding of the content material has another advantage in which a change in the quality of the content material can be prevented. The vertical sealing operation of joint portion 5 of films needs to terminate the packaging operation only for several seconds, but for some reason, there may be a case in which terminating the packaging operations for a longer time may be required. In such a case, if the content material remains unmoved in a pipe while the feeding operation is being terminated, a change in temperature may cause the viscosity of the content material to be changed. The change in viscosity may cause the amount of feeding content material that is being fed into tubular film to vary. For this reason, as in the present embodiment, it is preferable to ensure that the content material is being circulated during the time when the feeding operation is being terminated, thereby assuring uniform temperature of the content material and suppressing the above problem from occurring.

After the above vertical sealing operation is performed for a predetermined time, as shown by time t₁ (see FIG. 8), an ordinary packaging operation is resumed. More specifically, squeezing rollers 45 are opened, the content material is dropped downward (see FIG. 7D), three-way-valve 25 is switched, and the operation of feeding the content material into tubular film is resumed. Subsequently, the ordinary packaging operation is repeated as described above so as to continuously manufacture packaging bags.

Hereinbefore, an embodiment of the present invention has been described, but the present invention is not limited to the above configuration and various modifications can be made. For example, the packaging bag is not limited to the pillow type, but a three-way seal type or a four-way seal type may be used. For the pillow type, vertical sealed portion F1 (see FIG. 6) thereof is not limited to this, but a so-called butt-seam type or an envelope type may be used.

Both vertical sealing mechanism 30 and lateral sealing mechanism 60 of the packaging machine shown in FIG. 3 perform a box-shaped motion, but the present invention is not limited to this, and a general vertical sealing mechanism and lateral sealing mechanism for performing heat sealing in situ without moving up and down may be used. Packaging machine 10 of FIG. 3 is provided with the pair of squeezing rollers 45, but the present invention is not limited to this, and may be configured as a packaging machine without a squeezing roller.

With respect to injection nozzle 15, as shown in FIG. 10A, the injection port thereof may be formed at lower end 15 a of the nozzle or as shown in FIG. 10B, injection port 17 may be formed on the outer periphery surface of the nozzle. For the configuration of FIG. 10B, liquid level height h1 can be located higher than injection port 17 after squeezing rollers 45 are opened as shown in FIG. 7E. This assures that injection port 17 is not exposed to air, and the content material inside the nozzle is not dropped into the tubular film and remains in the nozzle. As a result, the same advantage of the present invention as described above can be obtained. 

1. A vertical filling-packaging machine comprising: an injection nozzle for feeding content material that is fluidized into a tubular film that includes a bottom portion; a transporter configured to transport the tubular film downward in a state in which the content material is fed thereinto; and a lateral sealing mechanism for tightly sealing the tubular film by heat sealing a portion of the tubular film, wherein the vertical filling-packaging machine manufactures a packaged product by a series of packaging operations including at least following operations: an operation of feeding the content material through the injection nozzle; an operation of transporting the tubular film downward in a state in which the content material is fed thereinto; and an operation of heat sealing by the lateral sealing mechanism, wherein an injection port of the injection nozzle is configured to be immersed in the content material throughout entirety of the series of packaging operations, and the operation of feeding the content material starts in a state in which the injection port of the injection nozzle is immersed in the content material.
 2. The vertical filling-packaging machine according to claim 1, further comprising a pair of squeezing rollers which pinches the portion of the tubular film in which the fed content material is present, and which rotates in a state in which the pair of squeezing rollers which pinches the portion of the tubular film in which the fed content material is present, thereby forming a flat void-filled portion on the tubular film and transporting the tubular film downward, wherein the operation of feeding the content material is to feed the content material into the tubular film that is located higher than the portion that is pinched by the pair of squeezing rollers.
 3. The vertical filling-packaging machine according to claim 2, wherein the content material that has been accumulated in a position higher than that of the squeezing rollers is dropped downward into the tubular film located lower than the squeezing rollers at the same time when the pair of squeezing rollers is opened, and after the content material is dropped, liquid level of the content material is configured to be higher than the injection port of the injection nozzle.
 4. The vertical filling-packaging machine according to claim 1, further comprising a content material feeding mechanism including: a reservoir tank for reserving the content material; a feed passage for transferring the content material from the reservoir tank to the injection nozzle; pump means used as a driving source for transferring the content material from the reservoir tank to a side of the injection nozzle; a return passage for returning the content material from the side of the injection nozzle to the reservoir tank; and valve means capable of switching between an operation of feeding the content material, which has been transferred through the feed passage, into the tubular film through the injection nozzle and an operation of returning the content material, which has been transferred through the feed passage, back to a side of the reservoir tank.
 5. The vertical filling-packaging machine according to claim 4, further comprising: a film feeding device which holds two feed rolls, joins an end portion of a first film drawn from one of the feed rolls to an end portion of a second film drawn from the other of the feed rolls, and feeds the joined first and second films as a long film; and a vertical sealing mechanism which performs vertical sealing on side edge portions of the long film along a longitudinal direction of the long film so as to change the long film into the tubular film, wherein the vertical sealing mechanism performs vertical sealing on a joint portion in which the first film and the second film are joined in a state in which an operation of transporting the long film is terminated, and the valve means of the content material feeding mechanism is switched to a position on a side of returning the content material to the side of the reservoir tank while the vertical sealing operation is being performed on the joint portion.
 6. The vertical filling-packaging machine according to claim 5, wherein the time to perform vertical sealing on the joint portion is longer than the time to perform an ordinary vertical sealing so as to prevent the content material from leaking from a vertical sealed portion formed by the vertical sealing.
 7. A method of manufacturing a packaged product, comprising a series of packaging operations, said series comprising at least following operations: feeding content material that is fluidized through an injection nozzle into a tubular film that includes a bottom portion; transporting the tubular film downward in a state in which the content material is fed thereinto; and tightly sealing the tubular film by heat sealing a portion of the tubular film in a lateral direction, wherein an injection port of the injection nozzle is configured to be immersed in the content material throughout entirety of the series of packaging operations, and the operation of feeding the content material starts in a state in which the injection port of the injection nozzle is immersed in the content material.
 8. The method of claim 7, further comprising pinching the portion of the tubular film in which the fed content material is present with a pair of rotating squeezing rollers, thereby forming a flat void-filled portion on the tubular film and transporting the tubular film downward, wherein the operation of feeding the content material is to feed the content material into the tubular film that is located higher than the portion that is pinched by the pair of squeezing rollers.
 9. The method of claim 8, wherein the content material that has been accumulated in a position higher than that of the squeezing rollers is dropped downward into the tubular film located lower than the squeezing rollers at the same time when the pair of squeezing rollers is opened, and after the content material is dropped, liquid level of the content material is configured to be higher than the injection port of the injection nozzle.
 10. The method of claim 7, further comprising transferring the content material from a reservoir tank wherein through a feed passage to the injection nozzle.
 11. The method of claim 10, wherein a pump drivers the transferring of the content material from the reservoir tank to a side of the injection nozzle.
 12. The method of claim 11, further comprising returning the content material from the side of the injection nozzle to the reservoir tank via a return passage.
 13. The method of claim 12, switching a valve between (a) feeding the content material, which has been transferred through the feed passage, into the tubular film through the injection nozzle and (b) returning the content material, which has been transferred through the feed passage, back to a side of the reservoir tank.
 14. The method of claim 13, further comprising: joining an end portion of a first film drawn from a first feed roll to an end portion of a second film drawn from a second feed roll; feeding the joined first and second films as a long film; and vertically sealing on side edge portions of the long film along a longitudinal direction of the long film so as to change the long film into the tubular film.
 15. The method of claim 14, wherein, in a state in which an operation of transporting the long film is terminated, a joint portion in which the first film and the second film are joined are vertically sealed, and the valve is switched to a position on a side of returning the content material to the side of the reservoir tank while the vertical sealing operation is being performed on the joint portion.
 16. The method of claim 15, wherein the time to perform vertical sealing on the joint portion is longer than the time to perform an ordinary vertical sealing so as to prevent the content material from leaking from a vertical sealed portion formed by the vertical sealing.
 17. A vertical filling-packaging machine comprising: an injection nozzle for feeding content material that is fluidized into a tubular film that includes a bottom portion; transport means for transporting the tubular film downward in a state in which the content material is fed thereinto; and a lateral sealing mechanism for tightly sealing the tubular film by heat sealing a portion of the tubular film, wherein the vertical filling-packaging machine manufactures a packaged product by a series of packaging operations including at least following operations: an operation of feeding the content material through the injection nozzle; an operation of transporting the tubular film downward in a state in which the content material is fed thereinto; and an operation of heat sealing by the lateral sealing mechanism, wherein an injection port of the injection nozzle is configured to be immersed in the content material throughout entirety of the series of packaging operations, and the operation of feeding the content material starts in a state in which the injection port of the injection nozzle is immersed in the content material. 